TimeKeeper/questionGenerators/math/numbers2.php

<?php

/**
 * "Find the missing number" sequence generator.
 *
 * Changes from the current repo version:
 *  - difficulty() returned the int 1 for a new user and the code then indexed
 *    it like an array (null values, notices on PHP 7.4+/8); it always returns
 *    ['percent' => .., 'count' => ..] now
 *  - user escaped in SQL; the hard-coded `e107.` database name replaced by
 *    MPREFIX
 *  - the previous tkLastQuestion row is removed before inserting the new one
 *    (each question used to add another row)
 *  - the token from TkAnswerStore::issue() is built once, before the form
 *  - leftover commented-out debug line removed
 */
class numbers2 {

    private $user;

    /**
     * Setup new numbers engine
     *
     * @param string $user User to supply the question for.
     */
    public function __construct($user) {
        $this->user = $user;
    }

    public function getNumbers() {
        $difficulty = $this->difficulty();
        $question = $this->getSequence($difficulty);
        $questionHtml = $this->htmlify($question);

        $db = e107::getDb();
        $db->delete('tkLastQuestion', "user = '" . $db->escape($this->user) . "'");
        $db->insert('tkLastQuestion', ['user' => $this->user, 'LastQuestionHtml' => base64_encode($questionHtml)]);

        e107::getRender()->tablerender('Numbers', $questionHtml);
    }

    /**
     * Difficulty based on the last month of answers.
     *
     * @return array ['percent' => float 0-100, 'count' => int]
     */
    private function difficulty() {
        $db = e107::getDb();
        $stats = $db->retrieve(
            "SELECT (SUM(correct)/COUNT(correct)*100) AS percent, COUNT(correct) AS count
             FROM `" . MPREFIX . "tkReport`
             WHERE answereddatestamp >= UNIX_TIMESTAMP(NOW() - INTERVAL 1 MONTH)
             AND username = '" . $db->escape($this->user) . "' AND subject = 'numbers'"
        );

        if (!is_array($stats) || (int) $stats['count'] === 0) {
            return ['percent' => 0, 'count' => 0];
        }

        return ['percent' => (float) $stats['percent'], 'count' => (int) $stats['count']];
    }

    private function getSequence($difficulty) {
        $count = (int) $difficulty['count'];
        $percent = (float) $difficulty['percent'];

        $startingNumber = mt_rand(0, (int) pow($count, ($percent / 100) * 2));

        if ($count >= 300) {
            $incrementalNumber = mt_rand(1, 100);
        } elseif ($count >= 200) {
            $incrementalNumber = mt_rand(1, 10);
        } elseif ($count >= 100) {
            $incrementalNumber = mt_rand(1, 5);
        } else {
            $incrementalNumber = mt_rand(1, 2);
        }

        $missingNumber = mt_rand(1, 10);
        $TempQuestion = [];

        for ($i = 1; $i <= 10; $i++) {
            if ($i == $missingNumber) {
                $TempQuestion[] = "___,";
                $solution = round($startingNumber);
            } elseif ($i == 10) {
                $TempQuestion[] = round($startingNumber);
            } else {
                $TempQuestion[] = round($startingNumber) . ",";
            }

            if ($percent >= 90 && $count >= 200) {
                $startingNumber += round((2 * $incrementalNumber) / $i);
            } elseif ($percent >= 80 && $count >= 100) {
                $startingNumber += $incrementalNumber * ($i * 15);
            } else {
                $startingNumber += $incrementalNumber;
            }
        }

        return ['answer1' => $solution, 'question' => $TempQuestion, 'type' => 'numbers'];
    }

    private function htmlify($question) {
        // Expected answer stays on the server; the form only carries a token.
        $token = TkAnswerStore::issue($this->user, $question);

        $frm = e107::getForm();

        $fString = $frm->open('questionForm', 'post', '', ['autocomplete' => 'off', 'class' => 'formclass']);
        $fString .= $frm->label('<h4>Numbers</h4>') . "</br>\n";
        $fString .= $frm->label('Find the missing number.') . "\n";
        $fString .= '</br>';

        foreach ($question['question'] as $seq) {
            $fString .= $frm->label($seq . " &nbsp; ") . "\n";
        }

        $fString .= '</br></br>';
        $fString .= $frm->text('a1', '', 80, ['placeholder' => 'Write answer here!', 'autocomplete' => "off", 'spellcheck' => "false"]) . "\n";
        $fString .= $frm->hidden('checkerData', $token, ['id' => 'checkerData']);
        $fString .= $frm->hidden('subject', 'numbers', ['id' => 'subject']);
        $fString .= '</br>' . "\n";
        $fString .= $frm->button('Answer', 'Check answer') . "\n";
        $fString .= $frm->close();
        $fString .= '</br></br>';

        return $fString;
    }
}